diff -r 000000000000 -r 6474c204b198 accessible/src/base/TreeWalker.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/accessible/src/base/TreeWalker.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,95 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_a11y_TreeWalker_h_
+#define mozilla_a11y_TreeWalker_h_
+
+#include "mozilla/Attributes.h"
+#include <stdint.h>
+
+class nsIContent;
+
+namespace mozilla {
+namespace a11y {
+
+class Accessible;
+class DocAccessible;
+
+struct WalkState;
+
+/**
+ * This class is used to walk the DOM tree to create accessible tree.
+ */
+class TreeWalker MOZ_FINAL
+{
+public:
+  enum {
+    // used to walk the existing tree of the given node
+    eWalkCache = 1,
+    // used to walk the context tree starting from given node
+    eWalkContextTree = 2 | eWalkCache
+  };
+
+  /**
+   * Constructor
+   *
+   * @param aContext [in] container accessible for the given node, used to
+   *                   define accessible context
+   * @param aNode    [in] the node the search will be prepared relative to
+   * @param aFlags   [in] flags (see enum above)
+   */
+  TreeWalker(Accessible* aContext, nsIContent* aNode, uint32_t aFlags = 0);
+  ~TreeWalker();
+
+  /**
+   * Return the next child accessible.
+   *
+   * @note Returned accessible is bound to the document, if the accessible is
+   *       rejected during tree creation then the caller should be unbind it
+   *       from the document.
+   */
+  Accessible* NextChild()
+  {
+    return NextChildInternal(false);
+  }
+
+private:
+  TreeWalker();
+  TreeWalker(const TreeWalker&);
+  TreeWalker& operator =(const TreeWalker&);
+
+  /**
+   * Return the next child accessible.
+   *
+   * @param  aNoWalkUp  [in] specifies the walk direction, true means we
+   *                     shouldn't go up through the tree if we failed find
+   *                     accessible children.
+   */
+  Accessible* NextChildInternal(bool aNoWalkUp);
+
+  /**
+   * Create new state for the given node and push it on top of stack.
+   *
+   * @note State stack is used to navigate up/down the DOM subtree during
+   *        accessible children search.
+   */
+  void PushState(nsIContent* aNode);
+
+  /**
+   * Pop state from stack.
+   */
+  void PopState();
+
+  DocAccessible* mDoc;
+  Accessible* mContext;
+  int32_t mChildFilter;
+  uint32_t mFlags;
+  WalkState* mState;
+};
+
+} // namespace a11y
+} // namespace mozilla
+
+#endif // mozilla_a11y_TreeWalker_h_